A magnetic disk drive includes a magnetic disk that records data, and a head slider that accesses the magnetic disk. The head slider has a head element that reads/writes data from/to the magnetic disk. The head element includes a recording element that converts an electrical signal into a magnetic field in response to recording data to the magnetic disk and a reproducing element that converts a magnetic field from the magnetic disk into an electrical signal.
The magnetic disk drive includes a carriage that moves the head slider to a desired position on the magnetic disk. The carriage is driven by a voice coil motor (VCM) and pivots around a pivotal shaft to move the head slider in the radial direction of the magnetic disk on the rotating magnetic disk. In this way, the head element accesses a desired track formed on the magnetic disk, so that data can be read/written therefrom/thereto.
The carriage includes an elastic suspension and the head slider is fixed to the suspension. The pressure caused by the air viscosity between the air bearing surface (ABS) of the head slider opposing the magnetic disk and the rotating magnetic disk balances with pressure applied in the direction of the magnetic disk by the suspension, so that the head slider can fly over the magnetic disk at a prescribed gap therebetween. The member made of the head slider and the suspension that supports the slider is called “head gimbal assembly” (HGA).
FIG. 6 is a view of a conventional HGA showing the structure of the HGA viewed from the side of the recording plane of the magnetic disk. As shown in FIG. 6, the HGA 400 includes a head slider 401, a suspension 402, and a lead 403. The lead 403 is a conductive wiring used to transmit a recording signal between the head element (not shown) formed at the head slider 401 and an amplifier portion (not shown) and/or a reproducing signal from the head element.
The suspension 402 includes a flexible flexure 404 that holds the head slider 401 on the side of the surface opposing the magnetic disk and a load beam 405 that holds the flexure 404 on the side of the surface opposing the magnetic disk. The shown HGA 400 is a load/unload type device and has a tab 406 at the tip end of the load beam 405 used to withdraw the device into a ramp mechanism.
The load beam is made of for example a layered material of a three-layer structure including stainless steel plates or two stainless steel plates and a polyimide resin layer provided therebetween (see for example Japanese Patent Publication No. 2005-190511 “Patent Document 1”). An edge part is bent in the length-wise direction of the load beam so that necessary rigidity is secured. The bent edge part of the load beam will hereinafter be called flange. The load beam 405 shown in FIG. 6 has a flange 407.
FIG. 7 is a sectional view of the HGA 400. The section in FIG. 7 is taken along the center of the slider 401 and in the width-wise direction of the HGA 400. A dimple 408 raised toward the side of the flexure 404 (upwardly in the figure) is formed in a position of the load beam 405 opposing the head slider 401. The flexure 404 bears on the load beam 405 as it is pressed against the dimple 408 by its own elasticity.
As shown in FIG. 7, the height H of the HGA 400 is determined based on the height of the head slider 401, the height of the flexure 404, and the height of the load beam 405. The height of the load beam 405 is determined based on the height of the dimple 408, the thickness of the thin plate that forms the load beam 405, and the height of the flange 407. Here, the height H of the HGA 400 refers to the thickness of the HGA in the orthogonal direction to the recording plane of the magnetic disk.
In recent years, with the advent of thinner magnetic disk drives, there has been a demand for HGAs having smaller heights. In order to reduce the height of the HGA 400 as shown in FIGS. 6 and 7, the height of the load beam 405 may be reduced. However, if the height of the flange 407 is reduced to reduce the height of the load beam 405, the rigidity (flexural and torsional rigidity) of the load beam 405 could be reduced, and necessary rigidity cannot be secured. Therefore, the extent of how much the height of the flange 407 can be reduced is limited in consideration of the rigidity of the load beam 405 that should be secured.
Note that an HGA disclosed by Japanese Laid-Open Utility Model No. 63-58372 (“Patent Document 2”) has its height reduced by bending the flange at the edge of the load beam in the opposite direction to the flange 407 in FIG. 7, in other words, it is bent to the side on which the slider is fixed. However, if such a structure is employed, it would be difficult to provide the flange around the slider in order to prevent the interference between the flange provided at the edge of the load beam and the slider or between the flange and the flexure or the lead provided around the slider. Therefore, the load beam could not have sufficient rigidity.